Paraämidophenyl-glyoxylic acid and process of making same.



* UNITED STATES PATENT FRITZ ACH, OF MANNHEIM, GERMANY, ASSIGNOR TO 0. F. BOEHRINGER & SOEIINE, OF MANNIIEIM-IVALDHOF, GFRMANY.

PARAAMIDOPHENYL GLYOXYLIC ACID AND PROCESS OF MAKING SAME.

ST'ECIFICATION forming part of Letters Patent No. 676,860, dated June 25, 1901. Application filed May 29, 1900. Serial Ila. 18,424. pecimens) To all whom, it may concern:

Be it known that I, FRITZ ACH, a citizen of the Empire of Germany, residing at Mannheim, in the Empire of Germany, have in- 5 vented certain new and usefullmprovements in Preparations of Paraamidophenyl-Glyoxylic Acid; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others IO skilled in the art to which it appertains to make and use the same.

This invention relates to the manufacture of amidophenyl-glyoxylic acids and in particular of paraamidophenyl-glyoxylic acid,

[5 its substitution products and homologucs, all of which are comprised under the general designation of paraamidophenyl-glyoxylic acids. Oflheseacidsonlyonerepresentative, para dimethyl amidophenyl glyoxylic acid (described in Berichte der Ghemisch Gesellschaft, Vol. 10, page 208,) has hitherto been known. A general method of preparation of this group of amido-ketone acids whose known representative has proved a highly active chemical reagent has not been found, and

hence a satisfactory study of the properties of this interesting group has been wanting.

I have discovered a method as a result of which this group may be readily produced, which is a matter of great importance, since they serve as the starting materials for the preparation of pharmacal products and dyestuffs. As a result of the experiments and researches in this direction I have found that the paraamidophenyl-tartronic acids which have been described in my application, Serial No. 731,674, filed September 25, 1899, are readily converted into the corresponding paraamidophenyl-giyoxylic acids when treated with mild oxidizing agents, carbon dioxid being split off coincidently.

My invention therefore,broadly considered consists in the oxidation of a paraamidophenyl-t-artronic acid.

The process, for example, in the case of preparing parai'tmidophenyl-glyoxylic acid proper from paraamidophenyl-tartronic acid proper is indicated in the equation:

y the ammonia as completely as possible.

coon

NHZCGIL.CO.OOOH+CO,+H2O.

As oxidizing agents I may employ peroxid of manganese, peroxid of lead, mercuric oxid, ferric chlorid, permanganate of potassium, arsenic acid, the. The oxidation may be performed in an alkaline as well as an acid solution. The resultant paraamidophenyl-glyoxylic acids form yellow crystalline products which decompose acetates and form yellowcolored phenylhydrazones with pheuyl-hydrazin, the crystalline chlorids of said hydrazones being soluble with diliiculty in water.

I will now describe my invention in detail by reciting a number of examples showing the preferred way of carrying my invention into eli'ect.

1. Preparation of parartmidophenyl-gli orylz'c acid (NII (J -H CO. 000 H) frompardamidophenyl iarironic crotch-For the purpose of a full disclosure I will first describe the mode of preparation and properties of the starting productthe paraamidophenyl-tartronic acid. Twelve parts, by weight, of aniliu-alloxan are gradually introduced, while stirring, into twenty-six parts, by volume, of potash lye, (KlIO-l-Aq,) which has ten times the strength of normal potash lye and which has been previously heated on a boiling-water bath. The anilin-alloxan is rapidly dissolved, while at the same time an energetic evolution of ammonia takes place. As soon as all of the anilin-alloxan has gone into solution the whole is subjected to evaporation while being stirred. Under this treatment the solution gradually thickens to a stiff crystalline semiliquid mass or paste comprising an aggregation of fine needles, which needles consist of the dipotassium salt of paraamidophenyl-tartronic acid. This crystalline mass is then dissolved in warm water and the resultant solution evaporated for driving off 5 The residue is thoroughly dried and is then dis generally square plates or tablets.

solved in about thirty-six parts, by weight, of water under the influence of heat, and the resultant alkaline solution is then acidulated with a suitable acidsuch as acetic acid, for example. Under this treatment the acid potassium salt of amidophenyl-tartronic acid is thrown out in the form of fine needles. This precipitate is then separated from the in otherliquor by siphoning, decanting, or in any other suitable manner after cooling. The remainder of the salt may be obtained from the mother-liquor by adding alcohol. In order to obtain the free acid, ten parts, by weight, of the acid potassium salt are dissolved in about two hundred parts, by weight, of warm water, 2.8 parts of potash lye (KI-10+ Aq) of ten times the normal strength being added. The resultant solution is treated with animal charcoal or other decolorizing agent and filtered, and the clear colorless filtrate is then treated with thirteen parts,by volume, ofa solution of hydrochloric acid having six times the strength of the normal acid. Thereupon the paraamidophenyl -tartronic acid is thrown out in the form of shining colorless needles, such precipitation generally taking place already before the solution has cooledotl. This crystalline mass after standing for a considerable time in the cold changes into a crystalline mass consisting of coarse After this mass has stood for some time in the cold the crystals are drained by siphoning or otherwise removing the mother-liquorand washed with some cold water. This acid is soluble in hot water with tolerable ease, more difficultly in alcohol. It cannot, however, be recrystallized from these solutions, since on heating the same carbonic acid is very soon evolved, the solutions becoming intensely yellow. lts formula is NH .O ,H .O H O The normal alkali salts (including ammonium salt) whichare readily soluble in water may be converted into the acid salts, which are difficultly soluble in cold water, by reacting thereon with acetic acid. Amidophenyltartronic acid is readily soluble without decomposition in dilutemineral acids and also in concentrated hydrochloric and sulfuric acids. On heating these solutions carbon dioxid, is very soon liberated. This acid has no sharply-defined melting-point. On heating the same it begins to turn yellow at 150 centigrade, and from that point it becomes progressively darker with the elevation of temperature until decomposition takes place at from 215 to 220 centigrade, the decomposition being accompanied by frothing. An ammoniacal solution of the acid reduces a silver solution in the heat with formation of a shining silver mirror. The paratmidophenyltartronic acid obtained as above or in any way is then subjected to oxidation in the following manner: A mixture of fifteen parts finely-powdered brownstone or \Veldon mud and two hundred parts of water is heated to the boiling-point, and at this temperature twenty parts of the acid potassium salt of paraamidophenyhtartronic acid are gradually introduced during the period of a quarter of an hour, the whole being constantlystirred. Vigorous evolution of carbonic-acid gas takes place, the reaction proceeding according to the equation:

coon l un ons-con +0:

After the whole has been introduced the mixture is boiled for about a quarter of an hour, whereupon thesame is placed on the filter hot to separate from the manganese sediment. To the filtrate soda solution (Na CO is added until the precipitation of carbonate of manganese ceases. Thereupon the filtrate is drained from the precipitate or sediment, evaporated down to twenty parts, and treated with carbon for (lecolorization, the, and hydrochloric acid is added until it reacts weakly acid on Congo paper. It is then allowed to stand in the cold for several hou rs,whereby the crystallization of the paraainidophenyl glyoxylic acid is completed. The resultant yellow product is redissolved in Water and treated with carbon (animal charcoal) for the purpose of further purification. From the resultant clear gold yellow solution when rapidly cooled the new acid is thrown out in the form of yellow fine shining needles and in the form of coarse brownish laminae when slowly cooled.

The paraamidophenyl-glyoxylic acid has no melting-point. On heating to 170 ccntigrade it turns brown and softens at about 190 centi' grade. On raising the temperature still higher it again attains a light yellow color and decomposes at a temperature above 400 centigrade. This new acid is readily soluble in warm alcohol and hot. water, but difficultly soluble in ether and benzene. It is, moreover, readily soluble in alkalies, ammonia, alkali carbonates, and on warming gently in dilute mineral acids.

If a solution of paraamidophenyl-glyoxylic acid is treated with a solution of chlorid of phenylhydrazin and the same is heated to 90 centigrade, a precipitate consisting of fine canary-colored needles is thrown down after a short time, said precipitate consisting of the chlorid of-phenylhydrazone. If this precipitate is dissolved in hot water and sodium acetate added thereto,the phenylhydrazone itself is thrown out in the form of fine yellow ncedles, which may be obtained in the form of short yellow prisms by rccrystallizing from alcohol of seventy-five per cent. strength. These crystals turn orange yellow on heating to 160 centigrade and melt with decomposition at 163 to 164 centigrade.

The anilin-alloxan or anil-alloxan used in the preparation of the starting product above as well as its mode of preparation have been described in Pelizzaris paper in the Gazetta C'ht'mt'ca, Vol. 17, page 412, et seq.

2. Preparation of1oara-dimethy Zamidophenyl-glyoa'yl't'c acid, (GH N.O H CO.COOI-I,

from para cZtmethyZam idophem Z tartrom'c f aci(Z.-The starting product for this reaction, thepara-dimethylamidophenyl-tartronic acid, has been described in my aforesaid applicacation, Serial No. 731,674, filed September 25, 1899. Its formula is (CH N.C II .O H O It crystallizes in coarse fiat prisms pointed at one end and decomposes at 109 to 110 centigrade, its decomposition being preceded by slight coloration and attended with frothing or effervescence. The said starting product is obtained from dimethyl-anil-alloxan, described by Pelizzari in Gazeta Oh't'mt'caltaliana, Vol. 17, page 412, et sea, by subjecting it to substantially the same treatment as given under the first example herein for the preparation of paraamidophenyl tartronic acid from anilin-alloxan, the proportions of mixture being of course governed by the different molecular weights, as will be readily understood.

In order to prepare the new glyoxylic acid, I take twenty-eight parts of the mono-potassium salt of para-dimethyl-amidophenyl-tartronic acid and introduce the same grad uallyv into a boiling mixture of three hundred parts of water and thirty parts of mercuric oxid suspended therein, the suspension mixture being stirred during the introduction. A vigorous evolution of carbon-dioxid gas takes place at this stage. After all of the phenyltartronic salt has been introduced the whole is kept Warm for a half-hour and continually stirred. The resultant solution is then drained from the residual sediment of mercury and unchanged oxid by placing the whole upon the filter. The filtrate is then acidulated with hydrochloric acid until the same shows a weak reaction on Congo paper, and it is then allowed to cool. The para-dimethyl-amidophenyl-glyoxylic acid is thereby thrown out in the form of small yellow shining foliated or lamellar crystals. The reaction resulting in this acid proceeds according. to the equation:

COOH

(OHQ N. O H COH +0 ()OOH cnpmc rn. co.coon+co,+n,o.

I was not able to establish melting-point of 187 centigrade, given by Michler and Hanhardt in Bert'chte der d. Ohemz'sch Gesellschaf, Vol. 10, page 2081. According to my observations the acid after having been several times purified will soften at a temperature of 150 centigrade and decomposes at 195 centigrade.

The phenylhydrazone of para dimethylamidophenyl-glyoxylic acid softens at 175 centigrade, and when the temperature is slowly raised from this point it decomposes at 181 centigrade.

5. Preparation of para-cZiethg Z-amidophenyZ-glyoatylic acid, (O H N. O H GO. 00 OH, rom para diethyl amidophenyl tariron ic acid.The starting product for this method, the para-diethyl-amidophenyl-tartronic acid, has been described in my aforesaid application, Serial No. 731,674. Its formula is (O H N. 0 11 0 11 0 It crystallizesin fine needles, which are decomposed with attendant frothing at 107 to 108 centigrade. The said starting product is prepared from diethylanil-alloxan, whose properties and mode of preparation are also set forth in, my aforesaid application, by subjecting it'to substantially the same treatment as given under the first example herein for the preparation of paraamido-phenyl-tartronic acid from anil-alloxan,the proportions of mixture being,of course, adapted to the different molecular weights, as will be readily understood. As will be seen from said application, Serial No. 731,674, the diethyl-anil-alloxan used in the preparation of the above starting material is prepared by heating its components, the diethyl-anilin and alloxan, in preferably molecular quantities in aqueous alcoholic solution, preferably in the presence of a Weak acid, such as acetic acid. The condensation product separates while the solution is still warm. When the same is completely thrown out, the motherliquor is drained and the residual condensation product is washed with water and a little alcohol. The formula of diethyl-anilalloxan is C l-I N O It is sparinglysoluhis in hot water, but readily in boiling alcohol, out of which it crystallizes in the form of coarse shining prisms. It softens at 190 centigrade and melts with decomposition at from 210 to 212 centigrade.

Proceeding now to the preparation of the new acid, I take forty-six parts of the monopotassium-salt of para-diethyl-amido-phenyltartronic acid and dissolve them in five hundred parts water. This solution is cooled to +4l centigrade and gradually poured into a solution of 15.5 parts of permanganate of potash in five hundred parts of Water, the second solution being also cooled to +45 centigrade. It should be observed that during the course of the reaction the temperature should at no time rise to above +5 centigrade. After the oxidation has been completed the resultant solution is filtered from the residual brownstone, the filtrate highly evaporated and decolorized and purified by treatment with carbon, (animal charcoal,) as will be readily understood, and then acidulated with hydrochloric acid until it reacts faintly on congo. By this treatment the major part of the new product, the para-diethylamido-pheny1-glyoxylic acid, is thrown out in a crystalline state, while the balance may be obtained by extraction with ether. The acid is then redissolved in benzene to which li groin has been added. Out of this solution it crystallizes in the shape of short yellow prisms aggregated in fan-shaped arrangement.

The reaction to which the production of the new acid is due proceeds according to the equation:

C'OOH I I E QQ 6 4 OOH O This new acid is readily soluble in alcohol,

aceticether,chloroform, acetone, in ether and hot water, in: alkalies, alkali carbo nates,.and dilute mineral acids. It softens when heated to 105 centigrade and melts at 114 to 116 centigrade to yellowish-red liquid, the melting being attended with evolution of gas.

The chl'orid of the hydrazone of the same crystallizes in shining straw-colored flatten-ed needles.

4. Preparation of parac'imido m'eta-toluylglyoscyl'ic acid (NH .O l l COzfiOO'fl) from parac'tmt'dmmeia-toluyZ-tartronic acid.For the purpose of a full disclosure I will first describe the mode of preparation and the prop erties of the starting product, the paraamid om eta-toluyl-tartron ic acid, which forms the subject-matter of my aforesaid application. Twenty-five parts,by weight,of ortho-tolu'idinalloxan is gradually introduced into fifty-two parts, by volume, of potash lye (KHO-l-Aq) of ten times normal'strength', which has been previously heated ona boiling-water bath, the introduction being accompanied by stirring. After the solution has been effected the same is evaporated to completely drive oif the ammonia. Theresidual crystallin-e'mass is then dissolved in. water, and this solution is also evaporated. The residue, which should be asd ry as possible, is brought into solution with a small amount of water (about five parts, by volume) and applicati'onof heat, (35 c'entigrade-) The clear brownish-yellow solution thus obtained is then slightly acidulated with any suitable acid-such, for example, as acetic acid. Upon adding tothis solution fromthree to four parts, by volume, of alcohol the acid potassium. salt of para.- ami'do-meta-t0luyl-tartronic acid is thrown out, and after the same has stood for sometime (about twenty hours) in the cold the mother-liquor is drained from the precipitate in any suitable manner-such, for example, as siphoning or decanting.

To obtain the free acid,the mono-potassium salt is dissolved in two parts, by volume, of water at a gentle heat, and. hydrochloric acid per. From. the solution thus prepared the new compound, paraamido-meta-toluyl-tarwarm in the form of needles groupedv in starshaped aggregations which are only slightly CH -c tor- .hot alcohol and moderately so in boiling water, from which it crystallizes in the form of l colored. Thecrystallization is completed af- 1 ter the solution has stood for sometime in the cold. This new acid, whose formula is NH .G H .O H O is readily soluble in mineral acids and dilute alkali-es, including ammonia. "will reduce an ammoniacal silver solution An ammoniacal solution of the same when heated, a silver mirror being formed.

. Itbegins to turn yellow when heated to over 5 150 centigrade. 3 above this pointthe compound gradually and i 1 progressively becomes darker until it is dark f brown. 7 1 composed, the decomposition being accom- On raising the temperature At 194 to I95 centigradeit is depanied by foaming or frothing.

The orth-otoluidin-alloxan from which the above starting material is obtained, as set forth in my above-specified application, Serial No. 731,674, is prepared by heating its components (toluid in and alloxan) together in preferably molecular quantities in aqueous alcoholic solution, preferably in the presence of acetic acid. The condensation product separates while the solution is still warm. When the same is completely thrown out, the

residual condensation product is washed with water'and a little alcohol.

The formula of the orthotol uidin-alloxan is It is solublewith difficulty in well-developed colorless obliquely-truncated prisms. At 220 centigrade it begins to turn to a brownish color, at 240 centigrade it softens, and it meltswith decomposition at 252 centi'grad e.

In preparing the new glyoxylic acid I take asolution of eighteen parts of the mono-potassium salt of the par'aam'ido-meta-toluyltartronic acid in three hundred and sixty parts of water, cool the same to +4 centigrade, and add thereto a cooled 4 centigrade) solution of 6.9 parts permanganate of potash in four hundred and twenty parts of water. The latter solution is added gradually and while stirring. After the oxidation is completed the sediment of brownstone is removed by filtering, and the filtrate is evaporated down to from fifty to sixty parts and then acidulated with hydrochloric acid until it reacts faintly on congo. After standing for several hours the glyoxylic or ketonic acid will have partly crystallized out of the solution and the mother-liquor is drained from the same, the balance of the new acid being obtained therefrom by extraction with ether.

The reaction which takes place in the formation of the new compound proceeds accordin-gto the equation:

COOH

ooou

Nmcar.oo.coou+co,+rr,o.

' mother-liquor is drained therefrom and the y For the purpose of purification it is redissolved in boiling water and is obtained from such solution in the form of yellow short needles aggregated in bundles or sheaves. It is readily soluble in alcohol, acetone, and acetic ether, but soluble with difficulty in chloroform and ether. On heating to about 150 centigrade the acid becomes'darker, and it melts at 163 to 164E centigrade with decomposition. The phenylhydrazone of the same is yellow and melts at 179 centigrade with decomposition.

5. Preparation of para-ethylene-d'iamidodiphenylglyoxyhc acid, O H,N H (G H,.OO. OOOH) from para-ethylene-diamido-diphenyl-tartr0nic act'cl.For the purpose of a full disclosure I will first describe the mode of preparation and the properties of the starting product,the para-ethylene-diamido-diphenyltartronic acid, (0 H, :N H O H G H O which forms the subject-matter of my aforesaid application, Serial No. 731,674. Five parts, by weight, of ethylene-diphenyl-diamido-dialloxan are dissolved warm in 10.5 parts, by volume, (corresponding to ten and one-half molecules,) of a solution of hydrate of potassium having ten. times the strength of normal potash-lye. The solution is evaporated until crystallization takes place. The crystals are then dissolved in water and the solution is again evaporated. The crystalline residue is then taken up with a minimum quantity of warm water (35 centigrade) and.

then acidulated with a suitable acid, such as, preferably, glacial acetic acid, and finally treated with alcohol. As a result of this treatment a concentrated aqueous solution of the acid potassium salt is first separated, which solution subsequently after standing for some time will be found to be in the form of a thick syrup covered by a layer of alcoholic lye.

, This supernatant lye may be poured off from the said syrup. The acid potassium salt of the new compound thus freed from the lye is then triturated with alcohol, whereby it is caused to assume a crystalline structure. The crystallized mono-potassium salt thus obtained is then dissolved warm in a little wa ter, (about three parts, by volume.) The resultant red solution is then treated with a decolorizing agent, such as animal charcoal, and filtered, and the filtrate is slightly acidulated with a suitable acid, such as hydrochloric acid, for example; The new compound paraethylene-diamido-diphenyl-tartronic acid is thus obtained in the form of a slightly-colored fine crystalline precipitate, which will form in spheroidal aggregates when crystallization takes place slowly. This new acid is readily soluble in alkalies and mineral acids. An ammoniacal solution of the same reduces an ammoniacal silver solution in the presence of heat with formation of a silver mirror. On heating the said new acid above 300 centigrade it gradually becomes dark brown, and it is decomposed without melting at a temperature above 400 centigrade. The formula of the new acid is The ethylene-diphenyl-diamido-dialloxan from which the above starting material is obtained, as set forth in my aforesaid application, Serial No. 731,674, is prepared by heating the components (the ethylene-diphenyldiamin and alloxan) together in preferably molecular proportions in aqueous alcoholic solution, preferably in the presence of acetic acid. The condensation product separates while the solution is still warm. When the same is completely thrown down, the motherliquor is drained therefrom and the remaining condensation product is washed with water and a little alcohol.

The formula of the condensation product ethylene-diphenyl-diamido-dialloxan is It is soluble with difficulty in alcohol. From a concentrated alcoholic solution of the same it is obtained in coarse shining prisms con,

taining one molecule C H O. At 215 centigrade these crystals stick together, and they darken and are decomposed without melting at 220 centigrade. Out of boiling water or dilute alcohol it crystallizes in fine acicular crystals, which soften at 190 centigrade and are decomposed at about 215 centigrade.

In preparing the present glyoxylic acid I dissolve ten parts of the acid potassium salt of the para-ethylene-diamido-diphenyl-tartronic acid in seventy-five parts of water and twenty-five parts of acetic acid and pour this solution gradually and while stirring into a mixture consisting of fourteen parts ofbrownstone (Weldon mud) suspended in seventyfive parts of boiling water. After the evolution of carbon-dioxid gas has ceased the boiling is continued for from fifteen to twenty minutes, and the resultant solution is then filtered from the sediment of brownstone and evaporated down to a considerable extent and slightly acidulated with hydrochloric acid. A brownish-yellow precipitate is thereby thrown down, which is then purified by redissolving in alkali and treating with carbon (animal charcoal) for decolorization, as will be readily understood,precipitating with H01.

The reaction by which the new acid is formed proceeds according to the equation:

This new acid, whose formula is is dissolved with difficulty in hot water and is thrown out of the same in the form of yellowish-brown granular crystals. In boiling water it is tolerably soluble, crystallizing therefrom after standing for some time in the form of indistinct crystalline spheroidal aggregations. On heating to about 175 centigrade the acid softens, and at 205 to 208 it melts with decomposition. In addition to the above the following acids of this group have been prepared by me by proceeding according to the method above described and substituting the corresponding tartronic acids.

6. Para-methyZ-amidophcnyZ-glyoacylic acid. (Formula: 0H,.NH.O lI .OO.COOH.)This acid crystallizes from hot Water in orange short and well-developed prisms. Itis readily soluble in boiling water, cold alcohol,acetone, and acetic ether, but soluble with diificulty in cold chloroform, ether, and benzene. It softens on heating to 140 centigrade and is decomposed with effervesccnce or frothing at 155 to 157 centigrade. The phenylhydrazone of the same crystallizes in small thick prisms, which melt with decomposition at about 164 centigrade.

7. Para-ethyl-amidophcnyl glyozryltc acid. (Formula: O H NH.C H .OO.O0OH.)This acid crystallizes from boiling benzene in the shape of orange-yellow lamellar or prismatic crystals, which begin to soften when heated to 113 centigrade and decompose with liberation of gas at 116 centigrade. It is very readily soluble in alcohol, acetone, and acetic ether, tolerably so in ether, and readilyin hot water, from which it crystallizes in well-developed yellowish-brown prisms. The chlorid of-itsphenylhydrazone crystallizes in canarycolored fine needles.

8. Pardethg Z amide-mcta-toZayZ-glyoocylic acid. (Formula: (J,H .NH.G,H .CO.OOOH.)- Readily soluble in hot alcohol, acetone, and acetic ether,and not so readilyin hot ether and water. 0 ut of a not too concentrated hot aqueous solution it crystallizes in the form of compact short small needles which are concentrically grouped in part. The acid melts at 132 to 134 centigrade when heated slowly, the melting being attended with frothing and dark-reddi'sh-brown coloration.

.9. Paradmt'do metamcthoxy -phcnyl-glyoxylic acid. (Formula: N11 011 00 11 00. O0OH.)Readily soluble-in boiling water, cold alcohol, acetone, and acetic ether, slightly soluble in ether, and crystallizes out of water in compact yellowish-brown concentricallyaggregated laminae or plates. O11 heating above 125 the acid becomes darker in color. It begins to soften at about 140 centigrade and melts with decomposition at from 147 to 148 centigrade.

10. Para phcnylamido phenyl glyomylic acid. (Formula: O H .NH.O H .OO.OOOH.)

1. Para-methyl bcnzyl cmnidophenyZ-glyowyli'c acid. (Formula: (CH (OJ-I :N.O H CO.COOH.)--This acid is precipitated out of water at first in the form of a yellow oil, which congeals or solidifies to long yellow acicular crystals. Out of dilute alcohol it crystallizes in the form of com pact fiat needles. It is readily soluble in alcohol, acetic ether, and acetone, tolerably so in ether, and less in boiling water. On heating to centigrade the acid begins to soften, and it melts at to 87 centigrade with liberation of gas.

What I claim, and desire to secure by Letters Patent of the United States, is

1. In the art of preparing a paraamidophenyl-glyoxylic acid, the process which consists in oxidizing a paraamido-tartronic acid.

2. The process which consists in adding to an oxidizing agent together with water an alkali salt of a paraamidophenyl-tartronic acid.

3. The process which consists in addingto an oxidizing agent together with water an alkali salt of a paraamidophenyl-tartronic acid, while agitating the mixture, then filtering and finally aeidulating the filtrate.

4. The process which consists in adding to an oxidizing agent together with water an al-- kali salt of a paraamidophenyl-tartronic acid while agitating the mixture, then filtering and finally aeidulating the filtrate, then cooling and redissolving and cooling rapidly.

5. The process which consists in introducing the acid potassium salt of paraamidophenyl-tartronic acid into a heated mixture of manganese dioxid and water.

6. The process which consists in introduc ing the acid potassium salt of paraamidophenyl-tartronic acid into a heated mixture of manganese dioxid and water, the addition being carried out gradually and while stirring, then boiling for a short time and filtering.

7. The process which consists in introducing the acid potassium salt of paraamidophenyl-tartronic acid into a heated mixture of manganese dioxid and water, the addition being carried out gradually and While stirring, then boiling for a short time and filtering, then evaporating the filtrate and aeidulating .with a mineral acid until weak acid reaction on eongo takes place and finally cooling.

8. The process which consists in introducing the acid potassium salt of paraamido phenyl-tartronie acid into a heated mixture of manganese dioxid and water, the addition being carried out gradually and while stirring, then boiling for a short time and filtering, then evaporating the filtrate and aeidulating with a mineral acid until weak acid reaction on congo'takes place, and finally cooling, then redissolving in water, adding carbon and rapidly cooling, whereby the resultant paraamidophenyl-glyoxylic acid is thrown out in acicular crystals.

9. As a new chemical compound paraamidophenyl-glyoxylic acid proper which has the formula hereinabove stated, is readily soluble in warm alcohol and hot water, in alkalies in- I composes at a temperature above 400, centicluding ammonia, alkali carbonates and on grade. 10 Warming gently in dilute mineral acids, but In testimony whereof I affix my signature soluble with difficulty in ether and benzene, in presence of two witnesses.

5 has no melting-point, turns brown on heating FRITZ AGH. to 170, centigrade, softens at about 190, cen- Witnesses:

ti grade, and on raising the temperature above LORENZ ACH,

this point again attains a light color and de- JACOB ADRIAN. 

